In photosystem II of purple bacteria, electrons flow through cytochrome bc, coupled to pumping of protons and the proton potential drives synthesis of ATP. The cytochrome bc complex transfers the electrons back to bacteriochlorophyll P870. This type of ATP synthesis is called
A) reverse electron flow. B) membrane potential. C) noncyclic photophosphorylation. D) cyclic photophosphorylation. E) proton motive force.